The problem

I am using wordpress with mysql both in a docker installation. The procedure for my setup is described here. Since mysql updated to version 8 they introduced caching_sha2 as the default password algorithm. When you use the auto update mechanism in wordpress everything is fine and wordpress still works with the native password version configured for the wordpress user. But if you use wordpress in a docker container and pull wordpress:latest there is a problem since wordpress 4.9.7 to access the mysql database: (Never thought I can use the word wordpress so many times in a sentence!)

The solution

The solution is relatively easy. You need to change the wordpress user manually from ​”mysql_native_password” to “caching_sha2_password“. This can be done with a simple SQL call. First stop your wordpress docker container and keep the mysql docker container running. Then execute these commands.

Setup a wordpress blog on docker with nginx as reverse proxy

Docker setup with wordpress, nginx and mysql containern

My friend und very experienced colleague Niklas Heidloff convinced me to start also a blog with all the geeky things I am doing all day long. In order to make it more interesting for me I decided to host wordpress on my own instead of using wordpress as a service (WaaS ?). Sylwester from Fablab.berlin pointed me to Vultr for hosting and so here we start. The idea is to have a simple docker setup with 3 containers. One for the Nginx webserver facing the evil internet and proxying the wordpress which is located in the local private docker network. Doing so I can also redirect to other web services (containers) later. Luckily there are already maintained docker container available for all 3 parts, so I only need to customize the nginx container with a dockerfile but can use the two others right as they are.

Install Docker on Ubuntu

Either you go with a docker provider like Bluemix or you get a virtual machine from softlayer or any other provider. In my case I have chosen a virtual server so I had to install docker on Ubuntu LTS. Which is really easy. Basically you add a new repository entry to your apt sources and install latest stable docker packages. There is also a script available on get.docker.com but I don’t feel comfortable to execute a shell script right from the net with root access. But it’s up to you.

wget-qO-https://get.docker.com/|sh

Docker on linux does not contain docker-compose compared to the docker installation for example on mac. Installing docker compose is straightforward. The docker compose script can be downloaded from github here: https://github.com/docker/compose/releases.

Docker-compose

Docker-compose takes care of a docker setup containing more than one docker container, including network and also basic monitoring. The following script starts and builds all docker container with nginx, mysql and wordpress. It also exports the volumes on the host file system for easy backup and persistence along docker container rebuilds and monitors if the docker containers are up and running.

docker-compose.yml

YAML

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version: '3'

services:

db:

image: mysql:latest

volumes:

-./db:/var/lib/mysql

restart: always

environment:

MYSQL_ROOT_PASSWORD: easytoguess

MYSQL_DATABASE: wordpress

MYSQL_USER: wordpress

MYSQL_PASSWORD: eveneasier

wordpress:

depends_on:

-db

image: wordpress:latest

restart: always

volumes:

-./wordpress:/var/www/html/wp-content

environment:

WORDPRESS_DB_HOST: db:3306

WORDPRESS_DB_USER: wordpress

WORDPRESS_DB_PASSWORD: eveneasier

WORDPRESS_DB_NAME: wordpress

nginx:

depends_on:

-wordpress

restart: always

build:

context: .

dockerfile: Dockerfile-nginx

ports:

-"80:80"

Mysql is the first container we bring up with environment variables for the database like username, password and database name. Line 7 takes care to save the database file outside the docker container so you can delete the docker container, start a new one and still have the same database up and running. Point this where you want to have it. In this case in “db” under the same directory. Also make sure you come up with decent passwords.

The second container is wordpress. Same here with the host folder on line 21. Furthermore make sure you have the same user, password and db name configured as in the mysql container configuration.

Last one is nginx as internet facing container. You expose the port 80 here. While you just specify a container in the other two, in this one you configure a Dockerfile and a build context to customize your nginx regarding to the network setup. If you only want to host static files you can add this via volume mounts, but in our case we need to configure nginx itself so we need a customized Dockerfile as described below.

Dockerfile for nginx setup

Dockerfile-ngin

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FROM nginx:latest

COPY default.conf/etc/nginx/conf.d/default.conf

VOLUME/var/log/nginx/log/

EXPOSE80

This dockerfile inherits everything from the latest nginx and copies the default.conf file into it. See next chapter for how to setup the config file.

Nginx config file

default.conf

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server{

listen80;

listen[::]:80;

server_name www.23-5.euansi.23-5.eu;

access_log/var/log/nginx/log/unsecure.access.log main;

location/{

proxy_read_timeout90;

proxy_connect_timeout90;

proxy_redirect off;

proxy_pass http://wordpress;

proxy_set_headerX-Real-IP$remote_addr;

proxy_set_headerX-Forwarded-For$proxy_add_x_forwarded_for;

proxy_set_header Host$host;

}

}

Line 2 and 3 configures the port we want to listen on. We need one for ip4 and one for ip6. Important is the proxy configuration in line 8 to 15. Line 11 redirect all calls to “/” (so without a path in the URL) to the server wordpress. As we used docker-compose for it docker takes care to make the address available via the internal DNS server. Line 13-15 rewrites the http header in order to map everything to the different URL, otherwise we would end up with auto generated links in docker pointing to http://wordpress

Start the System

If everything is configured and the docker-compose.yml, default.conf, Dockerfile-nginx and the folders db and wordpress are in the same folder, we can start everything being in this folder with:

start docker containers

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docker-compose up--build-d

The parameter “-d” starts the setup in the background (daemon). For the very first run I would recommend using it without the “-d” parameter to see all debug messages.